A conventional automatic transmission includes a hydrodynamic torque converter to transfer engine torque from an engine crankshaft to a rotatable input member of the transmission through fluid-flow forces. The transmission also includes frictional units, typically referred to as clutches, which couple the rotatable input member to one or more members of the planetary gearsets. Other frictional units, typically referred to as brakes, hold one or more members of the planetary gearsets stationary during the flow of power. Such transmissions also typically provide for one or more planetary gearsets in order to provide various ratios of torque and to ensure that the available torque and the respective tractive power demand are matched to each other.
One disadvantage of such known automatic transmissions is that it is more difficult with good planetary gearset design to provide an overdrive ratio of 0.75 or greater while yet achieving a gear ratio spacing in the transmission's lower gears (numerically higher gear ratios) that enhances vehicle drivability, performance, and fuel economy.